In the field of dyeing keratin fibers, in particular hair coloring, oxidation dyes have achieved significant importance. The coloration arises here as a result of the reaction of certain developer substances with certain coupler substances in the presence of a suitable oxidizing agent. The developer substances used here are, in particular, 2,5-diaminotoluene, 2,5-diaminophenylethyl alcohol, p-aminophenol and 1,4-diaminobenzene, while examples of coupler substances are resorcinol, 4-chlororesorcinol, 1-naphthol, 3-aminophenol and derivatives of m-phenylenediamine.
Besides dyeing to the desired intensity, numerous additional requirements are placed on oxidation dyes which are used for coloring human hair. For example, the dyes must be acceptable from a toxicological and dermatological point of view and the hair colorations achieved must have good light fastness, permanent wave fastness, acid fastness, and rubbing fastness. However, in any case, such colorations must remain stable over a period of at least 4 to 6 weeks without being affected by light, rubbing, and chemical agents. Furthermore, it is required that, by combining suitable developer substances and coupler substances, a broad palette of different color nuances can be produced.
For providing a natural coloration of the hair 1,3-dihydroxybenzene has been used in combination with p-phenylendiamine derivatives.
German Patent No. DE-A 32 33 541 suggests the use of substituted 1,3-dihydroxybenzene as couplers, nevertheless it is not possible to satisfy the above mentioned requirements in all aspects. Therefore there is a need for new couplers which provide natural colors for use in oxidative hair dyeing composition.